Work through the failure in order: confirm you are using the right Claude Code interface, check that the marketplace and plugin can be found, validate the plugin, verify it is installed and enabled for this session, then isolate the failing component. A plugin can install successfully while one of its skills, hooks, or MCP servers still fails at runtime. The steps below reflect Anthropic’s documentation as accessed October 4, 2026.
Identify where the failure occurs
Start with the exact error and the point at which it appears. Claude Code plugins pass through several distinct stages; an error at one stage does not necessarily mean the plugin package itself is broken.
| Failure stage | What to check first | Useful evidence |
|---|---|---|
| Command or interface | Whether you are in a supported Claude Code session rather than a regular shell or a different product surface | Where you entered the command and what responded |
| Marketplace lookup | Marketplace registration, spelling, source availability, and catalog freshness | Configured marketplace list and lookup error |
| Validation or installation | Manifest structure, marketplace entry, source path, and names | claude plugin validate output and installation error |
| Local installation or session loading | Installed/enabled state, install scope, and whether the current session loaded the plugin | claude plugin list, plugin details, and the /plugin Errors tab |
| Component runtime | The specific skill, command, hook, agent, MCP server, or executable that fails | Component inventory, its configuration, and its runtime error |
| Network or policy | Proxy, certificate trust, required hosts, or organization-managed restrictions | Debug output, /status where available, and administrator policy settings |
For the official troubleshooting and loading guidance, see Anthropic’s plugin troubleshooting and plugin loading reference.
1. Use the plugin command in the right interface
/plugin is an interactive command inside a supported Claude Code terminal session. Typing it directly into Bash, Zsh, or PowerShell does not open Claude Code’s plugin interface; the shell will treat it as a path or unknown command. Use claude plugin ... for plugin CLI operations in a shell, or start Claude Code and enter /plugin in its interactive terminal.
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First note where you expect the plugin to work: terminal, VS Code, Claude Desktop, or a cloud session. Plugin command and loading behavior can differ by surface, and a plugin available in one environment is not necessarily loaded in another. Anthropic documents the plugin interfaces and commands in its plugins overview.
2. Confirm the marketplace is registered and current
If Claude Code cannot find a marketplace or plugin, verify the configured marketplace and source before changing plugin files. The official marketplace is normally registered when an interactive terminal session starts, but automatic registration can be prevented by policy, an environment variable, or a failed setup attempt. The CLI plugin commands do not register it automatically.
-
In an interactive Claude Code terminal session, enter
/pluginand inspect the marketplace list for the expected source and exact spelling. -
If the official marketplace is missing, add it with
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If the plugin may have been added since the local catalog was cached, refresh that marketplace in the plugin interface, then search again.
-
For a private Git marketplace, confirm that the repository exists and that Git credentials can access it without interactive prompts. If cloning fails, check Git availability, SSH host trust, credentials, and clone timeout.
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A marketplace can be hosted on GitHub, at a URL, or at a local path. An offline refresh may leave a local catalog stale, so distinguish “not listed in this catalog” from “the plugin source is invalid.”
3. Validate the package and check its names and paths
Run claude plugin validate <path> against the plugin or marketplace. Validation can identify malformed JSON, missing required fields, and structural problems. A successful validation does not rule out an installation failure caused by an incorrect source path.
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Check relative paths. In a local marketplace, plugin paths are relative to the marketplace root: the directory containing
.claude-plugin/marketplace.json. Confirm the referenced directory exists relative to that root. -
Compare the marketplace entry and manifest names. The marketplace entry name is used in the install identifier; the plugin manifest’s
nameidentifies the plugin’s components. Confirm the names match as required by the marketplace documentation. -
Keep a published plugin’s name stable. Anthropic’s official plugin directory warns: “Once a plugin has been published, its
namemust not change — users have it installed under that slug, and renaming it breaks their install with aplugin-not-founderror.”
See the official plugin troubleshooting guide for common failed-install causes and the Anthropic-maintained plugin directory for the published-name guidance.
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4. Verify installation, enablement, and session loading separately
A marketplace is a catalog, an installed plugin is stored locally, and a plugin enabled for a given configuration must still be loaded into the current session. Check each state rather than treating them as interchangeable.
-
Run
claude plugin listto check whether the plugin is installed and enabled. -
Run
claude plugin details <name>to inspect the plugin and its component inventory. -
Check that the applicable settings enable the plugin and that its files are present under
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If you installed or updated the plugin after the current session started, use the plugin reload command described in the loading reference, or start a new session, then check whether the component is available.
Installation scope affects which configuration sees a plugin:
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User scope: applies across projects for that user.
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Project scope: is represented in the repository’s
.claude/settings.json. -
Local scope: applies to the user in that repository.
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Confirm that the scope where the plugin was installed matches the session and repository where you are testing it. Cloud sessions do not load plugins from local settings.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.5. Isolate the failing plugin component
Use claude plugin details <name> to see what the plugin contains, then troubleshoot the component that is actually missing or failing. A plugin may load as a unit even though a particular command, hook, or server cannot run.
Skills and commands
If a skill or command is missing, check its directory placement, the plugin manifest’s custom paths, and any required frontmatter. Compare the files on disk with the plugin’s component inventory. If a skill appears in the inventory but Claude does not select it, that points to a discovery or task-match issue rather than a loading failure: check whether the skill description fits the task.
Hooks
Inspect the hook configuration and the exact error from the event that should trigger it. Confirm that the configured command exists, is executable in the user’s environment, and has its required permissions and environment variables. A hook may load but fail only when its event fires; a hook can also block the operation it guards.
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MCP servers
Check .mcp.json, the configured transport and command, startup errors, credentials, and whether the server can connect. Separate an invalid server configuration from a process that fails to start or a server that starts but never connects. If an MCP server works with --plugin-dir but not after installation, investigate whether the installed package path or its runtime environment differs. Anthropic’s troubleshooting guide covers these distinct failure symptoms.
Executables and dependencies
For any bundled executable or dependency, check that it is available in the environment where the plugin runs and that it can be downloaded or started there. Do not treat a successful installation as proof that every runtime component works.
6. Check network access, proxy settings, and organization policy
Installation and component startup can depend on different network destinations. Anthropic’s current network guidance names github.com for Git-hosted marketplaces and plugins, downloads.claude.ai for plugin executable downloads, and registry.npmjs.org for npm plugin installs and dependencies. Allowlist only the hosts required by the marketplace source and components you actually use.
On a managed network, check the configured HTTP(S) proxy and TLS trust store or certificate paths. Use Claude Code debug output and /status, where available, to confirm which configuration loaded. A proxy URL or certificate-authority error should be resolved before diagnosing the package as malformed. Refer to Anthropic’s enterprise network configuration and CLI reference.
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If errors point to policy, ask your administrator to check marketplace source allowlists or blocks, plugin installation policy, sideloading settings, and session-only loading restrictions. Organization-managed controls may not be overridden by local settings.
Use the error evidence to choose the next step
Keep the exact terminal or panel error and compare it with the relevant evidence: marketplace list, validation output, installed-plugin list, plugin details, the /plugin Errors tab, debug output, and network or proxy status. This makes it easier to distinguish discovery, installation, session activation, and runtime failures instead of repeatedly reinstalling a plugin whose actual problem is a hook, server, or policy restriction.
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